feat(uart): eliminates nonexistent functions

loop() calls Serial Events functions when those are declared. The way it was declared was forcing to alway call avalable() to then call an empty function. This commit fixes it.

Author: SuGlider

Diff for: cores/esp32/HardwareSerial.cpp

@@ -24,16 +24,13 @@
 #endif
 
 void serialEvent(void) __attribute__((weak));
-void serialEvent(void) {}
 
 #if SOC_UART_NUM > 1
 void serialEvent1(void) __attribute__((weak));
-void serialEvent1(void) {}
 #endif /* SOC_UART_NUM > 1 */
 
 #if SOC_UART_NUM > 2
 void serialEvent2(void) __attribute__((weak));
-void serialEvent2(void) {}
 #endif /* SOC_UART_NUM > 2 */
 
 #if !defined(NO_GLOBAL_INSTANCES) && !defined(NO_GLOBAL_SERIAL)
@@ -48,37 +45,35 @@ HardwareSerial Serial2(2);
 
 #if HWCDC_SERIAL_IS_DEFINED == 1  // Hardware JTAG CDC Event
 extern void HWCDCSerialEvent(void) __attribute__((weak));
-void HWCDCSerialEvent(void) {}
 #endif
 
 #if USB_SERIAL_IS_DEFINED == 1  // Native USB CDC Event
 // Used by Hardware Serial for USB CDC events
 extern void USBSerialEvent(void) __attribute__((weak));
-void USBSerialEvent(void) {}
 #endif
 
 void serialEventRun(void) {
 #if HWCDC_SERIAL_IS_DEFINED == 1  // Hardware JTAG CDC Event
-  if (HWCDCSerial.available()) {
+  if (HWCDCSerialEvent && HWCDCSerial.available()) {
     HWCDCSerialEvent();
   }
 #endif
 #if USB_SERIAL_IS_DEFINED == 1  // Native USB CDC Event
-  if (USBSerial.available()) {
+  if (USBSerialEvent && USBSerial.available()) {
     USBSerialEvent();
   }
 #endif
   // UART0 is default serialEvent()
-  if (Serial0.available()) {
+  if (serialEvent && Serial0.available()) {
     serialEvent();
   }
 #if SOC_UART_NUM > 1
-  if (Serial1.available()) {
+  if (serialEvent1 && Serial1.available()) {
     serialEvent1();
   }
 #endif
 #if SOC_UART_NUM > 2
-  if (Serial2.available()) {
+  if (serialEvent2 && Serial2.available()) {
     serialEvent2();
   }
 #endif